This invention relates to processing apparatus, in particular to processing chambers for the processing of photographic material.
It is normal in photographic processing machines to use the chemicals that are carried in the reaction tanks to heat the mechanical components of the machine as well as the interior of the processor. It is also well known to use a heated water bath to surround the reaction chambers to heat them and the mechanical components in the processor. While this ensures stable temperatures can be maintained easily it has the disadvantage of holding the active chemicals at elevated temperatures for long periods of time. This leads to oxidation of the chemicals and loss of performance. This may be acceptable if the machine usage, and hence replenishment, is frequent but in walk up kiosk type machines usage can be very sporadic. A further disadvantage when using solutions to heat instant access kiosk type machines is that it must be ensured that the chemicals give the correct reactions. Keeping the chemicals hot over long periods would entail frequent additions of fresh chemicals, thus increasing both waste and cost. The chemicals could be kept cool but heat up times would add an unacceptable delay to the walk up instant features of a kiosk type processor.
It is known that some processors use fresh chemistry each time and rely on hot air to maintain the empty process chamber temperature over long periods of inactivity. A typical processor of this type is disclosed in U.S. Ser. No. 09/920,495, the contents of which are herein incorporated by reference.
The invention aims to provide a method and apparatus in which the above mentioned problems are overcome. As the chemicals required in these processors are of a very small volume it is necessary to bring them to a uniform and optimum temperature quickly and maintain it during the process. To this end it is important to ensure even and uniform air temperatures in the machine by avoiding stagnant or dead areas in the chamber. It is also necessary to transfer the heat quickly and uniformly from the air to the processing drum and then to the chemicals.
This invention overcomes the limitations imposed by having to heat large volumes of liquid and hold them for long periods while maintaining their activity. The invention also ensures uniform air distribution in the chamber and good heat transfer to the processing drum and chemicals.
According to the present invention there is provided an apparatus for processing a photographic material comprising an enclosure chamber, a processing chamber located within the enclosure chamber and adapted to hold the material therein, means for rotating the processing chamber and means for heating and circulating air throughout the enclosure chamber, the processing chamber being provided with at least one fin around the outer periphery thereof
Preferably a closed end of the processing chamber or drum is provided with at least one impeller fin.
The present invention further provides a method of maintaining uniform temperature in a processing apparatus, the apparatus comprising an enclosure chamber, a processing chamber located within the enclosure chamber and adapted to hold material therein, means for rotating the processing chamber and means for heating and circulating air throughout the enclosure chamber, the processing chamber being provided with at least one fin around the outer periphery thereof, the processing chamber being rotated continuously, whether or not material is being processed within the processing chamber, thereby continuously moving heated air around the enclosure chamber.
The fins on the outside periphery of the drum and the impeller fins radiating out from the centre on the back plane of the drum increase the surface area, improving the mass to surface area aiding heat transfer while the back impeller fins move the air around the enclosure chamber as the drum rotates.
A uniform temperature distribution is achieved, using air to heat both the process and the machine. This aids in uniform processing of a material along its length.
The temperature variation of the process chemicals is reduced along the length of the material and from strip to strip of material. It is possible to maintain the processing machine at a uniform temperature over long periods of inactivity. Warm up time for single use kiosks is eliminated due to the chemical temperatures quickly and uniformly reaching the set running temperature of the chamber as the drum rotates and the processing solution rolls around the inner surface of the drum. The invention also reduces the need to hold large volumes of chemicals at elevated temperatures which eliminates long term aerial oxidation in the processing chambers. The volume of chemicals in the machine is reduced as the chemical solutions can be drawn off as they are required, heated and then disposed of after use. The life time of the chemicals is thereby prolonged as they can be kept in cool airtight containers which may be sealed at the manufacturing plant and then drawn off, in single use volumes, by the processing machine through an airtight interface coupling such as the type used in the Kodak xe2x80x98SMxe2x80x99 chemical management system mini-labs.